Plants vs Zombies 2: Get more keys and plant food

In Plants vs Zombies 2, you go through many different levels, defeating zombies using your plants, which double as warriors, so that they don’t get to your lawnmowers, or get to your house. Keys allow you to open the locks on the map, which allow you to unlock bonuses such as new plants, more plant food and all of that jazz. Plant food, of course, allows you to uncork the full power of your plants, at least for about 10 seconds.